1. Field of the Invention
The present invention relates to a seal for a fluid meter and to a meter equipped with the seal.
It relates in particular to a water meter with a volumetric measuring chamber.
2. Description of the Prior Art
A prior art meter of the above kind comprises a casing or tank having an inlet pipe and an outlet pipe into which is inserted an oscillatory piston type volumetric measuring chamber. The measuring chamber has at least one inlet orifice and at least one outlet orifice. This kind of meter is well known to the person skilled in the art.
In some arrangements of the measuring chamber, the inlet orifice or the outlet orifice is provided at a particular height on the lateral wall of the envelope of the chamber. This orifice must be connected in sealed fashion to the corresponding inlet or outlet pipe, and to this end a seal is fitted into a groove formed around the orifice on the external face of the envelope of the chamber. Once the measuring chamber has been placed in the tank, the seal is clamped into the slot between the measuring chamber and the tank and ensures sealed flow of the fluid between the orifice and the corresponding pipe.
The prior art seal is a generally rectangular O-ring whose shape corresponds to that of the orifice.
Assembly is effected by placing the seal in its groove on the measuring chamber and then inserting the measuring chamber into the tank.
To provide a seal, the diameter of the unstressed seal is greater than the width of the slot between the measuring chamber and the tank. Upon inserting the measuring chamber, the seal is therefore subjected to forces in a direction opposite to the direction in which the measuring chamber is inserted into the tank. These relatively high forces can expel the seal from the groove, the seal then separating from the measuring chamber, with the risk of the measuring chamber being assembled to the tank with no seal, making the meter useless, or deform it in the direction opposite to the insertion direction, or even cut it. These problems are incompatible with mass production assembly of the meter.